{"id":7887,"date":"2013-06-21T12:16:17","date_gmt":"2013-06-21T19:16:17","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=7887"},"modified":"2013-06-21T12:16:54","modified_gmt":"2013-06-21T19:16:54","slug":"ultra-high-lift-without-flaps","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/ultra-high-lift-without-flaps\/","title":{"rendered":"Ultra High Lift Without Flaps"},"content":{"rendered":"

Dr. Gecheng Zha<\/a>, an Associate Professor with the University of Miami has an impressive set of credentials, culminating in a Ph.D.from the University of Montreal, Ecole Polytechnique. \u00a0 That, and his impressive body of work helped impress the audience at the seventh annual Electric Aircraft Symposium this last April.<\/p>\n

His work over the last decade has focused on generating high lift and low drag through circulation control on wings \u2013 even leading to the concept that wings can generate thrust instead of drag.\u00a0 This integration of aerodynamic forces would lead to highly efficient aircraft capable of flying on little \u2013 or even no power.<\/p>\n

Earlier attempts to increase lift and decrease drag have relied on sometimes complex, multiply flapped and slotted wings which require powerful mechanical actuators to work their magic. Others have used rotating cylinders laid spanwise on wing leading and trailing edges, or active suction or blowing to achieve their goals. \u00a0Zha has looked at these and other approaches, including synthetic jets and plasma jets for circulation control.<\/p>\n

His claims for the resulting Co-Flow Jet (CFJ) airfoil are pretty startling, and \u00a0hints of possible applications could be game changers in military, civilian and \u2013 importantly to the CAFE Foundation \u2013 Personal Air Vehicle (PAV) arenas.<\/p>\n

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Dr. Zha’s Co-Flow Jet (CFJ) airfoil showing flow attachment at over 40-degree angle of attack. Note wide discontinuity in airfoil that represents large slot in wing<\/p><\/div>\n

The airfoil injects air into a span-wise \u201cslot\u201d in the wing toward the leading edge, sucks air from that slot toward the trailing edge, and is driven by a low-power pump inside the airfoil. \u00a0The simple system provides high lift and low drag throughout the entire flight regime, instead of just during landings and takeoffs, as with flaps and slots.\u00a0 Wind tunnel tests show that the CFJ \u00a0flow between leading and trailing edges transfers energy to the air flowing over the wing\u2019s surface \u201cvia turbulent mixing under severe adverse pressure gradient.\u201d\u00a0 This Zero Net Mass Flow (ZNMF) keeps the main flow attached with induced large circulation, improved boundary layer control and consequent high lift.<\/p>\n

Besides generating high lift, CFJ reduces drag to the point where it may even provide thrust (much like what John McGinnis proposes with his box-wing configuration), and increases the stall margin over an expanded range of angles of attack.\u00a0 It works with any thick or thin airfoil, places small demands on the aircraft\u2019s powerplant, and can be applied to a wide range of aircraft.<\/p>\n

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Patent diagram showing Zha discrete co-flow jet wing on blended-wing future airliner<\/p><\/div>\n

With higher lift and lower drag, wings can be smaller, stall speeds can be lower, and something like the vision below might make even high-speed transport possible from true neighborhood airports.\u00a0 Such aircraft will be quiet enough<\/a> to be good neighbors because they lack the noisy wake mixing brought about by high-lift flap system deployment.<\/p>\n

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CFJ technology could make it possible to land jets on your street – the ultimate (but still fictional) personal aircraft<\/p><\/div>\n

The wide, open slot with its large discontinuity in the upper wing surface generates enhanced mixing of the spanwise and streamwide vortices structure of ZNMF, far exceeding theoretical limits.\u00a0 Dr. Zha has a patent pending on these breakthrough ideas and is looking for investors and collaborators to help make his ideas into practical flying hardware.<\/p>\n